Very small area flip chip die that have several spaced electrical contacts on one surface are well known. Such contacts are typically connected by soldering or the like to corresponding metalized regions on a circuit board or other support board which contains various electrical components with which the die is connected by traces on the board. With the constant push toward miniaturization, semiconductor die are made as small as possible to conserve circuit board area. However, as the die dimensions shrink, the contact areas of the die also shrink, limiting the current capacity of the die and increasing the difficulty of mounting and soldering the device to the board.
Die contacts having a circular topology and a height of about 260 μm have been developed for a FlipFet device by International Rectifier. The solder bumps of such devices may be used for currents of 0.5 to 1.0 amperes.
Also, a flip chip contact structure that can be reduced in area, while still having a relatively high current capacity is in demand. It would be desirable to provide a flip chip diode, which in one embodiment is square and may be about 60 mils on a side, and yet has a contact configuration that permits the die to operate as a 1.0 ampere FLIPKY (a trademark of International Rectifier Corporation) of the kind shown in U.S. Patent Application Publication No. 2004/0084770, filed on Nov. 6, 2002, and U.S. Pat. No. 6,653,740, filed on Feb. 9, 2004. In another embodiment, it would be desirable to provide a flip chip diode that is rectangular with possible dimensions of 1.244×0.914 mm for a 0.5 ampere type FLIPKY or other device.
Thus, the need exists for bump contacts and contact configurations that have low electrical and thermal resistance and do not unduly restrict the current capacity of the die. Also, the need exists for bump contacts and contact configurations that have greater than a minimum shear strength, avoid die tilting during normal use and installation into the circuit board, and avoid bump contact bridging. Higher shear strength improves package robustness when the die is mounted on the board, particularly in applications in which manual handling of the end product may take place. Further, the need exists for a die design that diminishes the chance for solder bridging with the anode pads.